"Crazy cat lady" but paying well above market and pays early every time. How much pressure should I keep on her?

[Vik Desai]

I've got 4 units that I rent out furnished and all bills paid.

My target market is guys coming into town for work and want to save compared to a hotel, Most of my contracts are month to month, I'm getting nearly double market rent, and I have a wait list (I know many of you are wondering about vacancies).

One lady has ended up with me in a long term situation and is happily paying the higher rent, uses less utilities than her neighbor, fixes her own stuff, even though I implore her not to and to let me pay my handiman to do it, and pays rent early.

I knew she had one cat.  One cat has turned into at least 6 litter boxes and taking in uncountable strays. I know the apartment stinks, I know that I'm going to have to pay a ton to fix it after she's out, I know that it's going to cost vacancy on top of the repair.

But she's paying....

I am putting some pressure on her to clean up, but with so many "Of course, Hun", and other pleasantries, I haven't really come down on her hard.

My thought is: 

I'm going to have to do the repairs no matter what. whatever damage she's caused is unlikely to get worse (she's been there over a year). What's the difference in doing it now and doing it in another 6 months or possibly years down the line?